Vehicle speed responsive controls for transmission, clutch and engine

ABSTRACT

The present invention relates to an automatic gearbox control device for automobiles which is applicable to any conventional mechanical gearbox and can be coupled to an existing vehicle without any major modification. The control device comprises : a source of pressure fluid, a double-action ratio-changing jack actuated by said pressure fluid through two electrovalves selectively, and an electrical regulating contactor propelled at a speed proportional to that of the vehicle and comprising two terminals selectively supplied with current by said regulator from the vehicle battery for supplying two connections to said electrovalves respectively, each of said connections comprising two contactors in parallel, namely a self-maintaining contactor activated by the ratio-changing member operatively connected to said jack and a maneuver contactor activated by the vehicle clutch i.e. which closes in the de-clutched position. The control device also includes means for automatically idling an associated engine or cutting off the fuel supply thereto during ratio shifting.

United States Patent Weymann 1 June 6, 1972 [5 1 VEHICLE SPEEDRESPONSIVE 2,662,621 12 1953 Long ..192/.092 CONTROLS FOR TRANSMISSION,2,703,636 3/1955 Long 192/.092 CLUTCH AND ENGINE Primary Examiner-Benamin W. Wyche [72] Inventor: Charles Terres Weymann, Paris, FranceAttorney-Jacobi, Lilling & Siegel [73] Assignee: S.I.D.A.R.O Societelndustrielle de Dispositifs Automatiques Robomatic, Oise, [57] ABSTRACTFrance The present invention relates to an automatic gearbox controldevice for automobiles which is ap licable to any conven- [22] 1970tional mechanical gearbox and can b: coupled to an existing {2}} A l, N26,305 vehicle without any major modification. The control devicecomprises a source of pressure fluid, a double-action ratiochanging jackactuated by said pressure fluid through two [30] Fore'gn Apphcat'onPnomy Dam electrovalves selectively,and an electrical regulating contac-Apr. 28, 1969 France ..6913392 impelled a Speed that vehicle andcomprising two terminals selectively supplied with current by 52 us. 01..192/.0s, 192/092, 192/358, said regulam' mm the vehicle suPPYmg192/084 74/873 91/189 nections to said electrovalves respectively, eachof said con- 51 im. c1. ..B60k 21/00, B60k 29/00 mpmmg cmacwrs inParallel namely a self 58 Field of Search 192/.062, .092, .08maintaining acivaed by the atiwhanging member operatively connected tosaid jack and a maneuver I 56] References Cited contactor activated bythe vehicle clutch i.e. which closes in the de-clutched position. Thecontrol device also includes UNITED STATES PATENTS means forautomatically idling an associated engine or cutting off the fuel supplythereto during ratio shifting. 2,605,874 8/1952 Price ..192/.0922,620,908 12/ 1952 Orr et al. 1 92/092 9 Claims, 6 Drawing FiguresPATENTEDJUN 6 I972 3,661 577 SHEET 1 [IF 3 PATENTEBM 61972 3,667,577SHEET 20F 3 I l a1 6v h H62 471 76 7c 7 FIG.3 FF

I FIG4 a 1 ,0 M E E A a FIG.5 I

PATENTEDJUH 6 I972 SHEET 3 BF 3 FIG. 6

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VEHICLE SPEED RESPONSIVE CONTROLS FOR TRANSMISSION, CLUTCH AND ENGINEThe present invention relates to an automatic gearbox control forautomobiles.

Automatic controls known up to the present generally require a specialgearbox, for example, with an epicyclic gearing, a hydraulic converter,a continuous variator, etcetera, and are generally adaptable only to avehicle designed for this purpose.

On the contrary, the present invention envisages an automatic controlwhich is applicable to any conventional mechanical gearbox; theautomatic control can be coupled to an existing vehicle without anymajor modification.

On the otherhand, the automatic control according to the invention canbe instantly disengaged if desired, simply by operating an electricalswitch. The conventional manual gearchange system, which remainsunaltered, is thus always available, giving total functionalreliability.

Again, a range selector allows optional choice of velocity stages forwhich the changes in ratio occur, so that the control is adaptable tothe preferred driving method of every driver.

Finally, as there is no modification to the vehicles transmission, andin particular there is no free-wheel in the control system, theadvantage of engine braking is always present, as in a conventional car.

The automatic control is just as suitable for threeor fourratio touringvehicles as for utility vehicles, lorries or buses which incorporate alarger number of ratios.

A device according to the invention for automatic control device for themechanical gearbox of a motor vehicle, comprising: a source of fluid ata pressure different from atmospheric pressure; a double-actionratio-changing jack, activable by said fluid, and whose piston rod isconnected to a ratio-changing member of the said gearbox; a first andsecond electro-valves interposed between said source and, respectively,both ends of the cylinder of said jack; and electrical regulatingcontactor, propelled at a speed proportional to that of the vehicle, andcomprising at least one first and one second output terminals,selectively supplied with current by said regulator, from the vehiclesbattery, for a first and a second range of velocities; a first andsecond electrical connection, respectively interposed between the firstoutput terminal and the first electrovalve, and between the secondoutput terminal and the second electrovalve, each of the saidconnections comprising two contactors in parallel, of which one is aselfmaintaining contactor activated by the said ratio-changing member,and of which the other is a maneuver contactor, activated by thevehicle's clutch, and which closes in the declutched position.

Embodiments of the invention will be described with reference to theaccompanying drawings, which are given by way of example only.

The drawings show in:

FIG. 1: a diagrammatic view of the device for controlling a two-ratiogearbox;

FIGS. 2,3: the positions for the first and second gear ratios of thede-clutch and self-maintaining switches;

FIG. 4: a diagrammatic view of the connection, by hydraulicconnecting-rod, between a gear-change jack and a gearchange lever;

FIG. 5: a supplementary jack used in a device for controlling afour-speed box;

FIG. 6: members which must be added to the device shown in FIG. 1 toensure control of a four-speed box.

With reference to FIG. 1, there will firstly be described an embodimentof a device which is applied to the control of a gearbox with two speedsonly. Generally, of course, automobiles have three or four gear ratios,or even more in the case of lorries, but description is simplified if itis illustrated in the case of a two-speed box. With reference to thefollowing F 168., a description will then be given of the inventionapplied to gearboxes with more than two ratios.

The device comprises: a gear change control servomechanism 1, afuel-throttling servomechanism 3, and a clutch servomechanism 5.

Each of these servomechanisms comprises at least one jack or hydraulicpiston and cylinder device activated by a fluid at a pressure differentfrom atmospheric pressure. In the embodiment in FIG. 1, all these jacksare pneumatic jacks activated by air, at a pressure below atmosphericpressure, which is stored in a tank 7 connected to a low-pressure tubefrom the engine.

servomechanism 1 comprises a double-acting jack 9, or ratio-changingjack which, via a piston rod 11, or through a liquid connecting-rodtransmission (not shown) controls a member of the gearbox, for example,the lever 13 of the gearbox. Two electrovalves 15,17 allow source 7 tobe connected selectively to one or the other end of jack 9. Whenelectrovalve 15 is activated, the piston of the jack and the rod 11 moveto the left, and bring lever 13 into a first ratio, indicated by ratioA. When electrovalve 17 is activated, lever 13 comes into the otherratio B. When neither of these electro-valves is activated, a returnsystem (not shown) brings the piston of jack 9 to the center, in theposition shown in the Figure.

Ratios A and B are two ratios on the same longitudinal axis and, forexample, for the most prevalent velocity ranges, these are thefirst-second, or else third-fourth gears.

servomechanism 3 likewise comprises a low-pressure jack 19, orfuel-control jack, whose piston rod is connected to the engine's fuelcontrol 21. An electrovalve 23, when it is activated, controls thethrottling of the fuel, and therefore the engines deceleration.

In the same way, servomechanism 5 comprises a low-pressure jack 25, orclutch jack, whose piston rod 27 controls a member of the vehiclesclutch system, for example, the clutch pedal 29. An electro-valve 31,when it is activated, controls the de-clutching movement (in thedirection of arrow D) of the vehicles transmission. servomechanism 5 canadvantageously form part of an automatic clutch control system.

The device further comprises a centrifugal regulating system 33, whichwill be indicated in the following by the term govemor." One inputterminal 35 of the governor 33 can be connected by a range switch 37 toone of the poles of the battery. The governor 33 which rotates at aspeed proportional to the vehicles road speed, closes an electricalcontact between the input 35 and a first output 39 for a first velocityrange (e.g. 0-30 km/h), corresponding to ratio AfFor a second velocityrange, e.g. above 30 km/h, the centrifugal regulator 33 opens the firstcontact and completes a second circuit, connecting input 35 to a secondoutput 41.

As will be shown in the following, the governor 33 comprises as manyoutputs as there are ratios to be controlled on the gearbox. On theother hand, as will likewise be shown, switch 37 may serve as a rangeselector in order to modify the extent of the different velocity rangeschosen.

The device also comprises a relay for controlling each ratio, in thecase of FIG. 1, a relay 43 corresponding to ratio A and a relay 45 forratio B.

The device finally comprises a first and second set of three switcheseach.

Switches 47,49,51 of the first set have mobile contacts, controlled bythe movements of the gearbox member controlling the changes in ratio.Thus piston rod 11 of servomechanism l is shown diagrammatically asactivating the mobile contacts of these switches.

Switches 53,55,57 of the second set have mobile contacts controlled bythe movements of the member controlling the clutch, for example, pistonrod 27 of servomechanism 5. Switch 47, with three contacts 47a, 47b,47c, controls the clutch electrovalve 31 in association with thecontacts of relays 43 and 45, which are respectively mounted in parallelwith contacts 47a, 47b and 47b, 470, as shown in dotted lines in FIG. 1.

Switch 53 controls the fuel electrovalve 23. The switch 55, or maneuverswitch, in association with the switch 49, or selfmaintaining switch,controls electrovalve 15. Switch 57 (maneuver), in association withswitch 51 (self-maintaining), controls electrovalve 17.

The different elements are electrically connected together according tothe circuits of FIG. 1, which shows the device at dead center.

The device functions as follows: with the engine running and the vehiclestationary, and lever 13 at dead center, the driver closes a feed-switch59 supplying governor 33 and terminal 47a of switch 47.

By means of circuit 47a,47c,53a, the current activates clutchelectrovalve 31. As soon as the clutch starts to travel, piston rod 27closes contactor 53 so that the current passing through 53a,53b, 61activates electro-valve 23, cutting off the fuel. Under thesecircumstances, even if the driver leaves his foot on the accelerator,the engine will idle.

When de-clutching is complete, piston rod 27 closes both contactors55,57, whose purpose will be described later.

When governor 33 is supplied with current and the vehicle is stationary,the current emerges from the governor by output 39, and activates thecoil of relay 43 mounted between the terminals 2,3 of this relay. Thecontact closes between terminals 1-4 of the relay.

The current emerging from terminal 39 of the governor 33 likewiseactivates the gear-change electrovalve through wires 63,63,53, andcontactor 55, which is closed, as shown previously. As a result of theopening of electrovalve 15, the piston of jack 9 moves to the left androd 11 brings lever 13 into the first ratio A, at the same time actingon contactors 47 and 49.

The mobile contact of contactor 47 is pushed to the left, maintainingcontact 47a-47b in force, but breaking contact 47b-57, for arm 47c isretained by a stop 67 in this direction (FIG. 2). The circuit47c,53a,53b,61 is therefore broken and deceleration electrovalve 23 isno longer excited. From this moment, therefore, the driver has theopportunity of accelerating normally. For the same reason, the excitercircuit of the clutch electrovalve 31 is likewise broken, making itpossible to engage the clutch.

If the vehicle is fitted with an automatic clutch control of the typedescribed, or with a centrifugal clutch, the driver then need onlyaccelerate in order to engage the clutch. On return into theclutch-engaged position, the three contactors 53,55,57 controlled by thepiston rod 27 open, but at first, this has no effects since it is nolonger in circuit, as was seen above. Contactor 55, closed until now,ensuring that electrovalve 15 was activated, is replaced in thisfunction by contactor 49 which is now closed (FIG. 2) and ensures thecontinuity of the exciter circuit of electrovalve 15 along the followingpath: 63 contactor 49 closed 64 65.

The vehicle is thus travelling normally in the first ratio A and, whenit reaches the speed provided for the change of ratio, the governor 33cuts off the current at output 39 and establishes the supply on output41.

The following operations are then carried out:

current in wire 63 is cut off; relay 43 is de-activated; contact 1-4 ofrelay 43 is opened; electrovalve 15 is de-activated.

current is established on terminal 41 of the governor 33; relay 45 isactivated; contact l-4 of relay 45 is closed.

the closure of contact 1-4 of relay 45, which is in parallel withcontact 47b-47c of contactor 47 which is at this point open, activatesthe de-clutching eIectro-valve 31 which is followed as stated above, bythe movement to the right of rod 27, by the closure of contactor 53causing activation of electrovalve 23, which cuts off the fuel, and bythe closure of contactors 55,57.

electro-valve 15 being de-activated, the left-hand part of jack 9 isexposed to the atmosphere, rod 1 1 moves to the right and brings lever13 to dead center as it activates contactors 47,49,51.

the whole is at dead center, clutch disengaged, fuel cut off, contactor47 closed, contactors 49 and 51 open (FIG. 1).

electrovalve 17 being activated, the right-hand part of jack 9 is putunder low pressure, pushing piston rod 11 to the right and causing lever13 to pass into ratio B.

piston rod 1 1, moving to the right, opens contact 47a,47b and closescontactor 51 (FIG. 3).

contact 47a,47b being open, the clutch electrovalve 31 ceases to beactivated, the clutch-engaged position is again adopted, as electrovalve23 is de-activated by the opening of contactor 53 (piston rod 27 movesto the left.) The fuel is thus no longer cut off. At the same time rod27 opens contactor 57, but electrovalve 17 continues to be activated viaclosed contactor 51.

- the car is then travelling normally in ratio B.

If the cars speed drops below the velocity provided for ratio B, andidentical procedure takes place, that is, output 41 of the governor 33ceases to be fed with current, and is replaced by output 39 whichactivates relay 43, whose contact 1-4, in parallel in open contact47a,47b, closes and controls the clutch disengagement, whileelectrovalve 17 ceases to be activated as a result of the lack ofcurrent on governor terminal 41.

The range selector 37, connected optionally by the driver, on the firstcontact 35 of governor 33 or on a second contact 70, allows choice ofthe vehicle speed at which changes of ratio will occur. For example, inthe case of a four-speed box, the changes will occur at 20-40-60 km/hfor the first change and at 30-50-80 km/h for the second change.

In order to simplify the description it has been supposed'up to now thatthe gear-change lever 13, or any other member of the gearbox, wascontrolled directly from the pneumatic jack 9. According to a preferredembodiment, a hydraulic transmission by fluid connecting rod betweenjack 9 and lever 13 is used, as is shown in FIG. 4.

Pneumatic jack 9 is fed with low-pressure air by one or other of theelectrovalves 15 or 17, as seen above, and its rod 72 activates thepiston 74 of an oil master cylinder both of whose ends are connected bytubes 78,80 to an oil receiver jack 82 whose piston rod 11 activateslever 13.

A tube 84, which incorporates a valve 86, connects both ends of thereceiver jack. If valve 86 is opened, the transmission by fluidconnecting-rod is eliminated and lever 13 can be operated manually. Itwill thus be seen that if the automatic control fails, the gear-changecan still be used manually. Valve 86 is preferably an electrovalve whichcloses when the supply contactor 59 of the automatic control (FIG. 1) isclosed. Thus one manual operation is enough to activate or de-activatethe automatic gear-change control.

Preferably also, the clutch disengagement electrovalve is excitedthrough a relay 87 shown in dotted lines in FIG. 1.

If one considers a range of velocities of four gears, such as that inFIG. 5, in which the gear-change lever 13 is returned to dead center onaxis III-IV by a spring, the device shown in FIG. 1 will be suitablewithout modification for carrying out the maneuvers III-IV and lV-III.

In order to adapt the device according to the invention to a four-speedbox, it is sufficient to add an extra jack, or selector jack, 88, whichis, for example, a low-pressure pneumatic jack. In this case governor 33comprises four outputs (FIG. 6), that is outputs 39 and 40 alreadydescribed (controlling ratios A and B, that is ratios III and IV for thefour-speed box), and two extra outputs 90-92 (respectively controllingthe first and second ratios I and II).

FIG. 6 does not show the entire device as in FIG. 1, the latterremaining unchanged, only the connector-points H and K on the circuitalready described (FIG. 1) being shown, and the extra memberscontrolling the change of gears into first and into second. This may bemore fully understood by viewing the governor 33 of FIG. 1 as possessingtwo additional output terminals 90 and 92. In fact, applicant has usedthe same reference numeral to indicate a similar device, thus one needonly imagine the similar input terminals 35 and 39 to the governor 33,thus the governor 33 would be connected, as in FIG. 1, to the controlswitch 47 (source 59).

In order to control a four speed box, all that is necessary is toconnect switch 49 of FIG. 1, to point H of FIG. 6 and to connect switch51 of FIG. 1 to point K of FIG. 6, switch 53 of FIG. 1 remainingconnected to point L.

The gear-shift lever 13 of FIG. 1 is movable from neutral positionlongitudinally in one or the other of two opposite directions into oneor the other of two speed-engaging positions; the gear-shift lever 13 inFIG. 6 is also movable in a transverse direction to a second neutralposition from which it may be moved longitudinally in one or the otherof two op posite directions into one or the other oftwo additionalspeedengaging positions. All of this may be done by the same system andin the same manner as described with reference to FIG. 1.

In order to move lever 13 into the second neutral position thereof, theinvention provides a piston having a piston rod 98 connected to lever13. The piston is responsive to fluid pressure controlled by theadditional output terminals 90 and 92 so as to move the lever 13 againstthe action of the resilient means (not shown) in the transversedirection to the second neutral position thereof, from which the leverwill be moved (by piston rod FIG. 11 of FIG. 1) into one or the other ofthe two speed-engaging positions corresponding to said additional outputterminals 90 and 92. This will be clearly apparent with reference to thediscussions found above. Thus, one may imagine that the line from switch59 to contact 47 A in FIG. 1 is thereby repeated in FIG. 6, thus it isclear FIG. 1 and FIG. 6 can be combined for the shifting of a four-speedtransmission.

These extra members in FIG. 6 comprise a relay 94, or firstgear relay,whose coil is activated by the current coming from output 90 of governor33, and a contactor 96 whose mobile contact is activated by the rod 98connecting the piston of selector jack 88 to lever 13.

The supply to low-pressure jack 88 is controlled by an electrovalve 100incorporated in a pipeline 102 linked to the lowpressure air source 7.

A relay 104, identical to relay 94, has its coil symmetrically connectedto output 92 (second gear output) of the governor, and is connected to acontactor 106 likewise activated by piston rod 98.

The start of the operation is identical to that described above, that isthe engine is de-clutched and the fuel mixture cut back, from circuit47a,47c,53a, activating the de-clutching electrovalve 31, thenelectrovalve 23.

At the same time, the vehicle being stationary, output 90 of thegovernor is under current, and supplies it to the coil of relay 94,whose terminals 3,4 are thus connected to terminal 1.

By means of the circuit output 90 contacts closed (1-4) of relay 94cable 108, the electrovalve 100 is excited and jack 88 brings lever 31into alignment 1-" of the range. At the same time, rod 98 closes contact96, which, by circuit 90 closed contacts l-3 of relay 94 closed contacts96a-96b-cable 110, puts point H under current.

Referring to FIG. 1, and to the associated description, it will be seenthat when point H is put under current, jack 1 is fed throughelectrovalve l5 and leads lever 13 to position A, that is, towards firstfor the four-speed range.

When the ratio-change speed provided for the passage from first tosecond is reached, output 90 ceases to be supplied, that is, point H isno longer under current, bringing about the results described withreference to FIG. 1: de-clutching, cutofi" of fuel, return of lever 13to dead center.

From this fixed speed, governor output 90 is supplied and, via thesymmetrical circuit of relay 104, and of contactor 106, the selectorjack electrovalve 100 is again excited in order to keep lever 13 in thealignment III of the range. At the same time point K is put undercurrent by the circuit 92-closed contacts 1-3 of relay l04-closedcontact 106.

With reference to FIG. 6 still, it will be seen that when point K isunder current, lever 13 is brought into position B, i.e. into the ratioof second on the four-speed range.

For the ratio changes third and fourth, the function is exactly the sameas that described with reference to FIG. 1,

respectively, for passing into ratios A and B, it being selfevident thatfor these two ratios electrovalve 100 of the selector jack 88 is neveractivated, since it can only be activated through outputs 90 and 92 ofthe governor. When jack 88 is not supplied, a return spring normallyreturns the gear lever 13 into alignment III-IV.

Naturally, the same combination would permit control of a six or eightspeed box, the basic elements remaining identical.

I claim:

1. In a motor vehicle having a change speed gear provided with agear-shift member, a friction clutch, a gas throttle member, and asource of electric current, an automatic gearchanging system comprising:a vehicle speed responsive governor connected to said source and havingat least two output terminals corresponding each to one of differentspeed ratios, respectively; first electromagnetically controlled meansoperative, when the electromagnet of said first means is energized, tomove said clutch from the engaged position into disengaged position;second electromagnetically controlled means operative, when theelectromagnet of said second means is energized, to move said throttlemember into idling position; third electromagnetically controlled meansoperative, when the electromagnet of said third means is energized, tomove said gear-shift member from its neutral position into onespeed-engaging position corresponding to one-of said different speedratios; fourth electromagnetically controlled means operative, when theelectromagnet of said fourth means is energized, to move said gear shiftmember from its neutral position into another speed-engaging positioncorresponding to another one of said different speed ratios; firstcircuit means comprising a first control switch for connecting theelectromagnet of said first controlled means to said source; secondcircuit means comprising a second control switch for connecting theelectromagnet of said second controlled means to a point of said firstcircuit means located between said first control switch and theelectromagnet of said first controlled means; third circuit meanscomprising a control switch and a first holding switch for connectingthe electromagnet of said third controlled means to one of said governoroutput terminals; fourth circuit means comprising a fourth controlswitch and a second holding switch for connecting the electromagnet ofsaid fourth controlled means to another one of said governor outputterminals; first switch-actuating means movable in unison with the axialmovements of said clutch, said first switch-actuating means beingconnected to said second, said third, and said fourth control switchesso as to close the same when said clutch reaches said disengagedposition thereof; and second switch-actuating means movable in unisonwith said gear-shift member and connected to said first control switch,and to said first and second holding switches so as to open said firstcontrol switch and to close said first and said second holding switcheswhen said gear-shift member reaches any of said speed-engaging positionsthereof.

2. A motor vehicle as recited in claim 1, in which said vehiclespeed-responsive governor has four output terminals two of whichcorrespond to said one and said other speed ratios and two other ofwhich correspond to two additional different speed ratios, and in whichsaid automatic gear-changing system further comprises fifthelectromagnetically controlled means operative, when said electromagnetof said fifth means is energized, to move said gear-shift member fromsaid neutral position thereof to a second neutral position from whichsaid gear-shift member is movable into a speed-engaging positioncorresponding to one of said two additional speed ratios or into anotherspeed-engaging position corresponding to the other of said twoadditional speed ratios; fifth circuit means comprising a fifth controlswitch for connecting said third circuit means comprising said thirdcontrol switch and said first holding switch to said fifth circuitmeans; a first relay connected to a first one of said two additionalgovernor output terminals and adapted, when energized through said firstoutput terminal, to connect said fifth circuit means and theelectromagnet of said fifth controlled means to said first outputterminal, sixth circuit means including a sixth control switch forconnecting said fourth circuit means comprising said fourth controlswitch and said second holding switch to said sixth circuit means; asecond relay connected to a second one of said two additional governoroutput terminals and adapted, when energized through said second outputterminal, to connect said fifth circuit means and the electromagnet ofsaid fifth controlled means to said second output terminal, and thirdswitch-actuating means movable in unison with said gear-shift memberbetween said neutral positions thereof and connected to said fifth andsaid sixth control switches soas to close the same when said gearshiftmember reaches said second neutral position thereof.

3. An automatic control device for the mechanical gearbox of a motorvehicle, the gearbox comprises a ratio-changing member, the motorvehicle comprises a battery, clutch having a control member, and anengine idler member, said automatic control device comprises;

a source of fluid at a pressure different from atmospheric pressure;

a double acting ratio-changing jack activated by said fluid; saidratio-changing jack piston rod is connected to said ratio-changingmember;

first and second electrovalves interposed between said source and,respectively, both ends of said ratio-changing jack cylinder;

an electrical regulating contactor, propelled at a speed proportionateto that of the vehicle and comprising at least first and second outputterminals selectively supplied with current by said regulating contactorfrom said battery, for a first and second range of velocity; I

a first and second electrical connection respectively interposed betweensaid first output terminal and first electrovalve, and between saidsecond output terminal and said electrovalve; each of said connectorscomprises two contactors in parallel, one of said contactors is aselfmaintaining contactor activated by said ratio-changing member, saidsecond contactor is maneuver contactor activated by the clutch, saidmaneuver contactor closes in the declutch position;

a de-clutching single-action jack, activated by said fluid;

said de-clutching jack piston rod is connected to said control member ofsaid clutch;

an electrovalve interposed between said source and said declutchingjack;

a relay;

an electrical connection between said battery and said electrovalve,said connection comprising two de-clutching contactors in seriesactivated by said ratio-changing member; said ratio-changing memberopens one or the other of said contactors when one or the other of saidgear ratios is interlocked, each of said contactors being mountedparallel respectively with the contactor of said relay, said relayincluding a coil energized by said output terminals of said electricalregulating contactor;

a single-action fuel-controlling jack activated by said fluid; saidfuel-controlling jack piston rod is connected to said engine idlermembers;

an electrovalve interposed between said source and said fuel-controllingjack;

an electrical connection between said battery and said electrovalve,said connection comprises an idler contactor means for activation at thestart of the de-clutching procedure by said member integral with saidclutch control member.

4. A device as recited in claim 3, wherein said de-clutching contactorsare combined into a single three-terminal declutching switch.

5. An automatic control device for a four-ratio mechanical gearbox of amotor vehicle, the gearbox comprises a ratiochanging member, the motorvehicle comprises a battery, a clutch having a control member, and anengine idler member,

said automatic control device comprises;

a source of fluid at a pressure difi'erent from atmospheric pressure;

a double-acting ratio-changing jack, activable by said fluid; saidratio-changing jack piston rod is connected to said ratio-changingmember of said gearbox;

first and second electrovalves interposed between said source and,respectively, both ends of said ratio-changing jack cylinder;

an electrical regulating contactor, propelled at a speed proportional tothat of said vehicle, and comprising at least one first and one secondoutput terminals, selectively supplied with current by said regulatingcontactor from said battery for a first and second range of velocity;

a first and second electrical connection, respectively interposedbetween said first output terminal and said first electrovalve andbetween said second output terminal and said second electrovalve, eachofsaid connections comprising two contactors in parallel, of which afirst of said contactors is a self-maintaining contactor activated bysaid ratio-changing member, and of which a second of said contactors isa maneuver contactor, activated by said clutch; and said secondcontactor closes in the de-clutch position and further comprises asecond ratio-changing jack, said second ratio-changing jack piston rodis connected to said ratio-changing member of said gearbox, said secondjack activating said ratio-changing member in transverse direction ifsaid firstmentioned ratio-changing jack activates said ratio-changingmember in the longitudinal direction;

a de-clutching, single-action jack, activated by said fluid;

said de-clutching ratio-changing jack piston rod is connected to saidcontrol member of said clutch;

an electrovalve interposed between said source and said declutchingjack; an electrical connection between said battery and saidelectrovalve, said connection comprising two de-clutching contactors inseries, activated by said ratio-changing member; said de-clutchingcontactors open one or other of said contactors when one or other ofsaid gear ratios is interlocked; a relay;

each of said contactors is mounted in parallel respectively with thecontactor of said relay; said relay including a coil energized by one ofsaid output terminals of said regulating contactor; a single-actionfuel-controlling jack, activated by said fluid; said fuel-controllingjack piston rod is connected to said engine idler member;

an electrovalve interposed between said source and said fuel-controllingjack;

a member integral with said clutch member;

an electrical connection between said battery and said electrovalve,said connection comprises an idler contactor activated at the start ofthe de-clutching procedure by said member integral with said clutchcontrol member.

6. A device as recited in claim 5, wherein said de-clutching contactorsare combined into a single three-terminal de- -clutching switch.

7. A device as recited in claim 6, comprises a low-pressure tube; saidsource of fluid at a pressure different from atmospheric pressure is anair tank at a pressure lower than atmospheric pressure, connected tosaid low-pressure tube.

8. A device as claimed in claim 7, comprises a fluid connector rod, saidratio-changing jack comprises a pneumatic jack connected to saidratio-changing member by said fluid connecting rod and further comprisesa master cylinder and a hydraulic receiver jack.

9. A device as recited in claim 8, comprising a hydraulic duct; a valve;both ends of said hydraulic receiver jack are interconnected by saidhydraulic duct fitted with said valve.

1. In a motor vehicle having a change speed gear provided with agear-shift member, a friction clutch, a gas throttle member, and asource of electric current, an automatic gear-changing systemcomprising: a vehicle speed responsive governor connected to said sourceand having at least two output terminals corresponding each to one ofdifferent speed ratios, respectively; first electromagneticallycontrolled means operative, when the electromagnet of said first meansis energized, to move said clutch from the engaged position intodisengaged position; second electromagnetically controlled meansoperative, when the electromagnet of said second means is energized, tomove said throttle member into idling position; thirdelectromagnetically controlled means operative, when the electromagnetof said third means is energized, to move said gear-shift member fromits neutral position into one sPeed-engaging position corresponding toone of said different speed ratios; fourth electromagneticallycontrolled means operative, when the electromagnet of said fourth meansis energized, to move said gear shift member from its neutral positioninto another speed-engaging position corresponding to another one ofsaid different speed ratios; first circuit means comprising a firstcontrol switch for connecting the electromagnet of said first controlledmeans to said source; second circuit means comprising a second controlswitch for connecting the electromagnet of said second controlled meansto a point of said first circuit means located between said firstcontrol switch and the electromagnet of said first controlled means;third circuit means comprising a control switch and a first holdingswitch for connecting the electromagnet of said third controlled meansto one of said governor output terminals; fourth circuit meanscomprising a fourth control switch and a second holding switch forconnecting the electromagnet of said fourth controlled means to anotherone of said governor output terminals; first switch-actuating meansmovable in unison with the axial movements of said clutch, said firstswitch-actuating means being connected to said second, said third, andsaid fourth control switches so as to close the same when said clutchreaches said disengaged position thereof; and second switch-actuatingmeans movable in unison with said gearshift member and connected to saidfirst control switch, and to said first and second holding switches soas to open said first control switch and to close said first and saidsecond holding switches when said gear-shift member reaches any of saidspeedengaging positions thereof.
 2. A motor vehicle as recited in claim1, in which said vehicle speed-responsive governor has four outputterminals two of which correspond to said one and said other speedratios and two other of which correspond to two additional differentspeed ratios, and in which said automatic gear-changing system furthercomprises fifth electromagnetically controlled means operative, whensaid electromagnet of said fifth means is energized, to move saidgear-shift member from said neutral position thereof to a second neutralposition from which said gear-shift member is movable into aspeed-engaging position corresponding to one of said two additionalspeed ratios or into another speed-engaging position corresponding tothe other of said two additional speed ratios; fifth circuit meanscomprising a fifth control switch for connecting said third circuitmeans comprising said third control switch and said first holding switchto said fifth circuit means; a first relay connected to a first one ofsaid two additional governor output terminals and adapted, whenenergized through said first output terminal, to connect said fifthcircuit means and the electromagnet of said fifth controlled means tosaid first output terminal, sixth circuit means including a sixthcontrol switch for connecting said fourth circuit means comprising saidfourth control switch and said second holding switch to said sixthcircuit means; a second relay connected to a second one of said twoadditional governor output terminals and adapted, when energized throughsaid second output terminal, to connect said fifth circuit means and theelectromagnet of said fifth controlled means to said second outputterminal, and third switch-actuating means movable in unison with saidgear-shift member between said neutral positions thereof and connectedto said fifth and said sixth control switches so as to close the samewhen said gear-shift member reaches said second neutral positionthereof.
 3. An automatic control device for the mechanical gearbox of amotor vehicle, the gearbox comprises a ratio-changing member, the motorvehicle comprises a battery, clutch having a control member, and anengine idler member, said automatic control device comprises; a sourceof fluid at a pressure different from atmospheRic pressure; a doubleacting ratio-changing jack activated by said fluid; said ratio-changingjack piston rod is connected to said ratio-changing member; first andsecond electrovalves interposed between said source and, respectively,both ends of said ratio-changing jack cylinder; an electrical regulatingcontactor, propelled at a speed proportionate to that of the vehicle andcomprising at least first and second output terminals selectivelysupplied with current by said regulating contactor from said battery,for a first and second range of velocity; a first and second electricalconnection respectively interposed between said first output terminaland first electrovalve, and between said second output terminal and saidelectrovalve; each of said connectors comprises two contactors inparallel, one of said contactors is a self-maintaining contactoractivated by said ratio-changing member, said second contactor ismaneuver contactor activated by the clutch, said maneuver contactorcloses in the de-clutch position; a de-clutching single-action jack,activated by said fluid; said de-clutching jack piston rod is connectedto said control member of said clutch; an electrovalve interposedbetween said source and said de-clutching jack; a relay; an electricalconnection between said battery and said electrovalve, said connectioncomprising two de-clutching contactors in series activated by saidratio-changing member; said ratio-changing member opens one or the otherof said contactors when one or the other of said gear ratios isinterlocked, each of said contactors being mounted parallel respectivelywith the contactor of said relay, said relay including a coil energizedby said output terminals of said electrical regulating contactor; asingle-action fuel-controlling jack activated by said fluid; saidfuel-controlling jack piston rod is connected to said engine idlermembers; an electrovalve interposed between said source and saidfuel-controlling jack; an electrical connection between said battery andsaid electrovalve, said connection comprises an idler contactor meansfor activation at the start of the de-clutching procedure by said memberintegral with said clutch control member.
 4. A device as recited inclaim 3, wherein said de-clutching contactors are combined into a singlethree-terminal de-clutching switch.
 5. An automatic control device for afour-ratio mechanical gearbox of a motor vehicle, the gearbox comprisesa ratio-changing member, the motor vehicle comprises a battery, a clutchhaving a control member, and an engine idler member, said automaticcontrol device comprises; a source of fluid at a pressure different fromatmospheric pressure; a double-acting ratio-changing jack, activable bysaid fluid; said ratio-changing jack piston rod is connected to saidratio-changing member of said gearbox; first and second electrovalvesinterposed between said source and, respectively, both ends of saidratio-changing jack cylinder; an electrical regulating contactor,propelled at a speed proportional to that of said vehicle, andcomprising at least one first and one second output terminals,selectively supplied with current by said regulating contactor from saidbattery for a first and second range of velocity; a first and secondelectrical connection, respectively interposed between said first outputterminal and said first electrovalve and between said second outputterminal and said second electrovalve, each of said connectionscomprising two contactors in parallel, of which a first of saidcontactors is a self-maintaining contactor activated by saidratio-changing member, and of which a second of said contactors is amaneuver contactor, activated by said clutch; and said second contactorcloses in the de-clutch position and further comprises a secondratio-changing jack, said second ratio-changing jack piston rod isconnected to said ratio-changing member of said gearbox, said sEcondjack activating said ratio-changing member in transverse direction ifsaid first-mentioned ratio-changing jack activates said ratio-changingmember in the longitudinal direction; a de-clutching, single-actionjack, activated by said fluid; said de-clutching ratio-changing jackpiston rod is connected to said control member of said clutch; anelectrovalve interposed between said source and said de-clutching jack;an electrical connection between said battery and said electrovalve,said connection comprising two de-clutching contactors in series,activated by said ratio-changing member; said de-clutching contactorsopen one or other of said contactors when one or other of said gearratios is interlocked; a relay; each of said contactors is mounted inparallel respectively with the contactor of said relay; said relayincluding a coil energized by one of said output terminals of saidregulating contactor; a single-action fuel-controlling jack, activatedby said fluid; said fuel-controlling jack piston rod is connected tosaid engine idler member; an electrovalve interposed between said sourceand said fuel-controlling jack; a member integral with said clutchmember; an electrical connection between said battery and saidelectrovalve, said connection comprises an idler contactor activated atthe start of the de-clutching procedure by said member integral withsaid clutch control member.
 6. A device as recited in claim 5, whereinsaid de-clutching contactors are combined into a single three-terminalde-clutching switch.
 7. A device as recited in claim 6, comprises alow-pressure tube; said source of fluid at a pressure different fromatmospheric pressure is an air tank at a pressure lower than atmosphericpressure, connected to said low-pressure tube.
 8. A device as claimed inclaim 7, comprises a fluid connector rod, said ratio-changing jackcomprises a pneumatic jack connected to said ratio-changing member bysaid fluid connecting rod and further comprises a master cylinder and ahydraulic receiver jack.
 9. A device as recited in claim 8, comprising ahydraulic duct; a valve; both ends of said hydraulic receiver jack areinterconnected by said hydraulic duct fitted with said valve.